In order to decrease cycle time and to insure good molding of either metal casting or injection molded plastic parts it is necessary to provide coolant flow passages within the mold apparatus for removing heat from the apparatus during the molding process. In the case of molding apparatus with a mold cavity part having a plurality of female cavities formed therein that receive core parts that cooperate with the female cavities to form the surfaces of a molded part, apparatus for cooling has included a round cooling tube that is formed by the interior surface of the core part. An example of such cooling apparatus is set-forth in U.S. Pat. No. 4,655,280.
One problem with such arrangements is that molded parts having an elongated configuration require a core with a length to width ratio that can cause the core to deflect when material is injected against the core under high pressure conditions. Since many materials are best shaped and densified under such high pressure conditions, one problem with prior art apparatus is how to provide a low cost core that will not deflect or warp under high temperature and high pressure operation.
Another problem with such molding apparatus is that the coolant flow is restricted to an annular surface that limits the removal of heat from each of the mold cavities.